IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of discharging bubbles in a head tank in a short time with a simple configuration.SOLUTION: A normally closed discharge valve 153 having a valve body 253 capable of opening/closing a discharge port 173 is provided in a discharge path 154 communicating with the inside of the head tank and having the discharge port 173, and a discharge cap 152 is provided which is fitted into the discharge port 173 to move the valve body 253 in a valve opening direction, and a sealing member for sealing between the inside of the head tank and the discharge port 173 is provided between the inner peripheral surface of the discharge path 154 and the outer circumferential surface of the valve body 253. A through-hole 174 is provided in the valve body 253, and when discharging the bubbles from the head tank, the discharge cap 152 is brought in direct contact with the valve body 253 to open the discharge valve 153, thereafter, the valve body 253 is moved by the discharge cap 152 to a position where the through-hole 174 communicates with the inside of the head tank 101 and the inner cavity 240 of the discharge cap 152, and in this state, a suction pump 53 is driven.